A broad array of topical personal care and personal hygiene products are available for application to human skin to counteract malodors associated with the human body, particularly those malodors resulting from and associated with perspiration. These products include sports and athletic sprays and powders, antiperspirants, foot and body powders, body sprays, and especially deodorants. Other types of products are available to absorb potentially destructive sebum oils and residues generated by the sebaceous glands within a person's skin. The ability to combat either of these undesirable results is quite favorable within the personal hygiene product industry and the search for new and effective additives for such purposes has existed for many years.
As examples, malodors may be “masked” or concealed by placing a sufficient amount of perfume composition in the deodorant in order to hide or cover the malodor. Perfumes provide the additional benefit of imparting a desirable fragrance, such as a variety of different fresh, pastoral, or musk scents, to a cosmetic or personal care product. However, “masking” also has distinct limitations. Unfortunately, some malodors cannot be masked simply by adding perfumes, because they are highly volatile (and therefore diffuse quickly into the air) or because they are extremely potent. Indeed, in some cases it may be impossible to add sufficient amounts of perfume in order to sufficiently conceal the underlying malodor without also giving the personal care product an overly strong, perfumed odor. Topical antimicrobials, such as triclosan, may also be applied to the skin since perspiration-associated body malodors are typically the result of interaction between microbes, perspiration and triglyceride secretions from the sebaceous glands, which combine to produce malodorous and pungent metabolites and/or fatty acids. Thus, by controlling the microbe population on the skin's surface, the malodor can be eliminated or reduced in intensity. However, the use of antimicrobial agents, particularly in excessive amounts, is strongly discouraged because it may contribute to the development and/selection of microbes resistant to known antimicrobial compounds. Additionally, the build-up of antimicrobial agents in the human body is suspected of potentially producing heretofore unknown side effects. Furthermore, the general molecular structures of some antimicrobials have been reported to cause skin irritation, obviously a result unwanted within skin treatment and personal hygiene formulations.
Another approach that avoids the aforementioned problems while also reducing malodor involves the use of odor absorbers, such as activated charcoal and zeolites. These odor absorbing compounds function by absorbing odors and perspiration, and unlike the aforementioned treatment compounds they do not irritate the skin or impart an overly perfumed scent to the composition. However, charcoal and zeolite odor absorbers have the disadvantage that as they get wet (e.g., they come into contact with perspiration) they can become ineffective at odor absorption. For similar reasons, these odor absorbers can also be difficult to formulate into compositions that contain even small quantities of water.
It had been realized that metal silicate additives provide excellent malodor protection as well as potential sebum absorption benefits within cosmetic, etc., compositions, such as within skin care and decorative cosmetics, as some examples. Unfortunately, it was also realized that such silicate materials generally exist at high pH levels that create problems for such formulations and compositions, particularly when they are present in amounts that are necessary for the desired malodor neutralization and/or sebum absorption benefits to occur during use. As a result, such materials may cause deleterious reactions and stability problems within such cosmetic, personal hygiene, skin treatment, etc., formulations and compositions (such as, as one example, rendering ineffective certain pH sensitive antiperspirant salts). Furthermore, certain materials, in particular antiperspirant salts, may deleteriously affect the performance of such malodor reducing compounds through ionic interaction between the cation of the metal silicate and the anion of the antiperspirant salt. It has been noticed that certain amounts of antiperspirant salts will gel, coagulate, or otherwise precipitate out of solution during storage when present simultaneously with uncoated/untreated metal (i.e., calcium) silicates. Although the amount of such antiperspirant salts is generally much higher than for the malodor-reducing calcium silicates, the overall effect has been found to render such calcium silicates less effective for their intended purpose and to reduce (although relatively slightly) the amount of the available salts for eventual precipitation on the target skin surface. There is thus a clear need to provide calcium silicate additives for such types of personal care compositions that exhibit lower pH levels during application of finished product forms in order to ensure the maximum effectiveness of all the additives present within such formulations. To date, no such improvement has been provided within the cosmetic formulation and/or personal hygiene product industries.